Flat Car Battery from non-use of car

Like many on this forum, I am over 70 and therefore under "house arrest" for the duration. One thing that's worrying me is that my car - an automatic - has been standing on the drive outside, with the alarm (and other electronics?) steadily draining the battery. I have no means of charging the battery "off-line".

So I have two questions for "me learned friends" ...

1. When a car is not driven for some time, how long before the battery goes flat, assuming battery is in good condition, and was charged on a 30 mile journey prior to lockdown?

2. Is it possible to use a 3S 3200 LiPo (or perhaps two in parallel) to jump-start the car if its battery does go flat? (And how would you set that up?)

hello Romeo, why not just go out for a 20 min run,once,twice a week...not meeting anyone ect….I wouldn't fancy trying the lipo touch.....am sure I read somewhere that a car standing with a healthy battery, would be ok for a few weeks...I may be wrong.

Alternatively, parts shops are open (as an essential trade), perhaps a helpful friend or neighbour could pick up a charger for you, or, maybe lend you one? Halfords do a basic charger for £30.

Answer to #1 - piece of string. Our relatively recent battery (~1 yr old) in the diesel passat was being a bit sluggish after several weeks, it had been used only for short journeys for the preceding two weeks, ie the last decent run was a month ago.

I have a maintenance charger connected up to my motorbike over the winter months. Like a modern car, new bikes are constantly drawing from the battery when not in use to feed alarm systems, immobilisers and other electronics. My Oxford maintenance charger monitors the battery voltage and when it drops below 12.6V, it applies a couple of hundred milliamps until the voltage rises to about 13.8V and then drops the current back to zero - the cycle repeats every couple of hours or so. What it's doing is displayed on an LCD screen. A standard battery charger for long term use is not advisable as it will usually drop to a low current and maintain a small charge indefinitely - this may lead to overcharge and possible damage to the battery over a long period e.g. over winter for several months. Car chargers will differ and some might have a maintenance mode, but I have known a few cheaper types that will constantly stuff an amp or more into a fully charged battery come what may.

The solar panel into a cigar lighter socket is a good idea, but some cars might disconnect the socket from the system after a time delay. My 08 Mondeo keeps the sockets connected, but the wife's 15 Fiesta doesn't.

Hi Romeo Whiskey . Most modern cars have sophisticated electronics that draw tiny current even when at rest. Provided your battery is in good condition it should be ok for at least three weeks and probably longer . If you can run a lead out to you car then a Ctek or similar charger/conditioner will maintain your battery for long periods of storage.Link.is for the Absaar model that is somewhat cheaper but a good little charger. I bought one of these a few years back and use it during the winter months when car is standing. If you do go for one of these make sure you buy one of sufficient capacity for you battery .

I did buy a solar powered battery trickle charger some years ago and was not impressed but solar panels have improved so may be a better option no summer is on its way ?

Another thing to think of during long lay ups is the general condition of the car , brakes etc . They will benefit from a drive around the block once in a while enough to get them hot and dry out any moisture that can cause corrosion .

You can still drive the car. I've got 2 cars, and take one out once a week to keep the battery charged, but found that both vehicles. As I didn't use one for over 4 weeks, as used the other for work (the V6 Vectra is mainly for shows) and when i did start it, started fine. But both batteries are new and in good condition. It takes around 20 mins of running to recharge an extended start, so if the car starts easily a drive for 20 to 30 mins at high speed should keep enough charge to enable future restarts.

Assuming that like most people on this forum, you have a multiple battery technology charger for model use that runs on 12v, you could charge your car battery on a Lead-Acid program using those LiPos as the power source. Much kinder on the cells, terminations and cabling than using them to jump start although I have heard of people using them in this way for emergencies.

Buy a pair of jump leads now before everyone realises they have the same problem in a couple of weeks.....

Then if you are a glow/petrol flyer then use your 12 volt model starter battery to start the car. Or if an electric flyer keep your car battery charged with your lipo charger set to lead acid. But if you are just a glider pilot bad luck - on your bike!

Seriously our little 12 volt batteries will start a car. Years ago at a show the seller of those cheap ex standby equip 12 volt 7 ah gel cells ( Proops i think ) said he used one of these cheap batteries to start his E type - I didn't really believe it but later found he was correct. They will start a car. However take all the precautions we used to take when running old cars in the 1960's in the 62/63 freeze. Free up the engine first by rocking the car in gear ignition off as the oil will be sticking a bit ( obviously we used a starting handle then! Younger people ask your grandfather what they are) Then keep your foot off the 'gas' and turn it over twice. Leave a minute try again. Repeat until it starts ensuring you dont touch the accelorator, if you have then keep the throttle wide open and turn the engine over with throttle wide open then leave a few minutes.Try again. If all else fails then its a push start - try using 3rd gear not 1st and get the car really moving before dropping the clutch. My car eventually started every day in the 62/63 freeze even though it was an old 1950 A40 Devon with ancient battery.

Thanks guys, info much appreciated. I always keep jump leads in the car as it's an auto, but cannot get another car very close to where I have to park it at home.

Also I can't easily use a trickle charger as there is no power point handy and the driveway is open plan. The idea of using one of my lipo chargers set to Lead Acid and powered by a Lipo is certainly an option I hadn't thought of.

I realised that taking it for a drive once a week is the obvious answer, and have done that with my wife's car, but as we depend on various neighbours to bring us food essentials I don't want them to get the wrong impression that we are flouting the govt rules. I also don't know how the local stasi would respond if I explained that's what I'm doing.

While we're on that subject I don't understand why plod is harrassing people exercising or walking dogs when they are clearly well above two metres away from anyone else. Don't they realise that for many people the beach or countryside is their local area?